Display panel

ABSTRACT

A display panel includes a plurality of pads, a plurality of first contacts connected to the pads, a plurality of second contacts provided so as to be opposed to the plurality of first contacts, a polysilicon layer configured to form a plurality of polysilicon films to connect the plurality of first contacts and second contacts, and a gate metal layer. The gate metal layer forms at least one gate metal. The gate metal layer traverses the plurality of polysilicon films so as to form a plurality of transistors. The plurality of transistors are arranged in a zigzag pattern for each transistor set. A width of a portion of each of the polysilicon films, the portion forming a corresponding one of the transistors, is larger than a width of another portion of the polysilicon films. The other portion is connected to a corresponding one of the first contacts and second contacts.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese application JP2009-231968 filed on Oct. 5, 2009, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display panel, in particular, adisplay panel including an inspection circuit for detecting defects.

2. Description of the Related Art

A liquid crystal display panel using thin-film transistors is known as adisplay panel and is widely used for a television set, apersonal-computer display, a cellular phone, and the like.

The liquid crystal display panel generally includes: a display region inwhich a plurality of pixels are formed; and a peripheral regionsurrounding the display region. In recent years, with an increase inarea of the display region, the peripheral region is reduced.Accordingly, it becomes difficult to ensure a space for providinginspection terminals in the peripheral region. The inspection terminalsare provided to turn the liquid crystal display panel ON for inspectionof the liquid crystal display panel. Therefore, as a method fordetecting a defect of the liquid crystal display panel, a pseudo dynamiclighting inspection (hereinafter, referred to as “QD lightinginspection”) is used (see JP 2004-101863 A and JP 2001-324721 A).According to the QD lighting inspection, the number of inspectionterminals can be reduced by providing an inspection circuit to theliquid crystal display panel.

FIG. 9 is a schematic diagram of a display panel in the related art. Adriver for driving liquid crystal (hereinafter, referred to simply as“driver”) provided to the display panel does not have an RGB switchingfunction. A part of a circuit other than drain lines is omitted in FIG.9.

As illustrated in FIG. 9, a display panel 900 includes a pixel regionsection 903 and a driver region section 980. In the pixel region section903, a pixel region 901 and inspection transistors 902 are provided. Inthe driver region section 980, a driver installation region 904 in whicha driver is provided, an R drain-line inspection terminal 905, a Gdrain-line inspection terminal 906, and a B drain-line inspectionterminal 907 are provided.

The inspection transistors 902 are provided in an area of the pixel areasection 903, which is situated on the opposite side to the driverinstallation region 904 as viewed from the pixel region 901. Theinspection transistors 902 are respectively provided so as to correspondto R-pixels, G-pixels, and B-pixels provided in the pixel region 901.Drains of the inspection transistors 902 are connected to an Rinspection wiring 908, a G inspection wiring 909, and a B inspectionwiring 910 according to RGB of the pixels in the pixel region 901.Further, the R inspection wiring 908, the G inspection wiring 909, andthe B inspection wiring 910 are respectively connected to the Rdrain-line inspection terminal 905, the G drain-line inspection terminal906, and the B drain-line inspection terminal 907 provided in the driverregion section 980. A gate of each of the inspection transistors 902 isconnected to a gate line terminal 912 provided in the driver regionsection 980 through an intermediation of a gate wiring 911. A wiringfrom a source of each of the inspection transistors 902 passes throughthe pixel region 901 to be provided in the driver installation region904.

In this case, there is a problem that breaking or short-circuitingcannot be detected for the wirings provided in an area from the driverinstallation region 904 to the pixel region 901.

Therefore, in the case where the driver has the RGB switching function,a configuration in which an inspection circuit is provided in the driverinstallation region is known as illustrated in FIG. 10. In FIG. 10, apart of the circuit other than the drain lines is omitted.

As illustrated in FIG. 10, a display panel 960 includes RGB switches 920provided in an area of the pixel region section 903, which is situatedbetween the driver installation region 904 in which the driver isprovided and the pixel region 901. RGB-switch terminals 921, 922, and923 are provided in the driver region section 980.

A source of each of the RGB switches 920 is connected to one of the R-,G-, and B-pixels provided in the pixel region 901. Gates of the RGBswitches 920 are connected to the RGB-switch terminals 921, 922, and 923through an intermediation of RGB-switch gate wirings 971, 972, and 973,for a corresponding one of the R-, G-, and B-pixels provided in thepixel region 901. After the RGB switches 920, each including threetransistors, are connected in parallel to each other, a drain of the RGBswitches 920 is connected to a source of each of the inspectiontransistors 930 by a wiring. Further, a drain-line inspection terminal941 is connected to a drain of each of the inspection transistors 930through an intermediation of a drain-line inspection wiring 940, whereasa gate line terminal 951 is connected to a gate of each of theinspection transistors 930 through an intermediation of a gate wiring950.

In comparison with the case illustrated in FIG. 9, switching can beperformed by the RGB switches 920 to conduct the QD lighting inspectionin this case. Therefore, the number of the inspection transistors 930can be reduced to one-third, which allows a large area to be ensured forthe inspection circuit including the inspection transistors 930. As aresult, even if output terminals of the driver become extremely fine, adesired width of each of the inspection transistors can be ensured.Moreover, the breaking or the short-circuiting of the wiring from eachof the output terminals of the driver to the pixel region can bedetected.

SUMMARY OF THE INVENTION

In the case where a driver without the RGB switching function is usedfor an LTPS-TFT panel, however, a sufficiently large width cannot beensured for each of the inspection transistors when the QD lightinginspection circuit is provided in the driver installation region in asimple manner. Therefore, there is a problem that the QD lightinginspection cannot be appropriately conducted. This problem is describedbelow referring to FIG. 11. FIG. 11 is a schematic diagram of aninspection circuit formed by simply arranging the inspection transistorsin one row.

As illustrated in FIG. 11, pads 140 for the driver, to which the outputterminals of the driver are connected, are connected by metal wirings151 to pad connection contacts 150 which are, for example, arranged in arow. Moreover, at the positions opposed to the pad connection contacts150, inspection wiring connection contacts 160 are provided. Each of thepad connection contacts 150 and a corresponding one of the inspectionwiring connection contacts 160 are connected to each other by apolysilicon film 120. By providing a single gate metal 130 across thepolysilicon films 120, inspection transistors 110 arranged in a row areformed.

The polysilicon films 120 are formed in a polysilicon layer, whereas thegate metal 130 is formed in a gate metal layer which is different fromthe polysilicon layer. Moreover, each of an R inspection wiring 181, a Ginspection wiring 182, and a B inspection wiring 183 is connected to acorresponding one of the inspection wiring connection contacts 160 byusing a metal wiring 184, a gate wiring 185 in the same layer as that ofthe gate metal 130, a contact 186, and the like.

In the configuration illustrated in FIG. 11, each of the inspectiontransistors 110 is formed by providing the gate metal 130 across each ofthe polysilicon films 120. The details of the formation of thetransistors and each of the layers are the same as those described belowin an embodiment of the present invention, and therefore are hereinomitted.

In this case, the width of each of the pad connection contacts 150 islimited by a distance between the pads 140 to which the output terminalsof the driver are connected, while a width of each of the inspectiontransistors 110 is limited by a width of each of the pad connectioncontacts 150. Specifically, the width of each of the inspectiontransistors 110 is limited by the distance between the output terminalsof the driver.

Therefore, there is a problem that a sufficient width cannot be ensuredfor each of the inspection transistors 110 when a highly sophisticateddriver with an extremely small distance between the output terminals isused. More specifically, for example, in the case where theconfiguration illustrated in FIG. 11 is used, a width of only 10 μm isensured as the width of each of the inspection transistors for theaforementioned reason, characteristics of polysilicon, and reasons interms of a method of fabricating the polysilicon layer, when the outputterminals of the driver are provided at intervals of 15 μm. For the QDlightning inspection by appropriately lighting the display panel, thewidth of the inspection transistor is required to be 13 μm or larger.Therefore, the aforementioned width is insufficient for the QD lightinginspection.

In view of the problem described above, the present invention has anobject to provide a display panel including an inspection circuit inwhich a desired width of an inspection transistor is ensured even if adistance between output terminals of a driver is extremely small in thecase where a driver used for the display panel is a highly sophisticatedone without an RGB switching function.

(1) A display panel according to the present invention includes: aplurality of pads configured to provide a driver thereon; a plurality offirst contacts respectively connected to the plurality of pads; aplurality of second contacts respectively provided so as to be opposedto the plurality of first contacts; a polysilicon layer configured toform a plurality of polysilicon films to connect the plurality of firstcontacts and the plurality of second contacts to each other; and a gatemetal layer different from the polysilicon layer. The gate metal layerforms at least one gate metal. The gate metal layer traverses theplurality of polysilicon films so as to form a plurality of transistors.The plurality of transistors are arranged in a zigzag pattern for eachtransistor set including at least one adjacent transistor. A width of aportion of each of the plurality of polysilicon films, the portionforming a corresponding one of the plurality of transistors, is largerthan a width of another portion of the each of the plurality ofpolysilicon films, the another portion being connected to acorresponding one of the plurality of first contacts and the pluralityof second contacts.

(2) In the display panel according to the item (1), the plurality oftransistors include a plurality of transistor rows, each including atleast two adjacent transistors, and the plurality of transistor rows arearranged in the zigzag pattern.

(3) In the display panel according to the item (2), a number of thetransistors included in each of the plurality of transistor rows is fouror less.

(4) In the display panel according to the item (2), the plurality oftransistor rows have an overlapping portion when the plurality of secondcontacts are viewed from the plurality of first contacts.

(5) In the display panel according to the item (2), a width of a portionof the each of the plurality of polysilicon films located between theplurality of transistor rows is smaller than the width of the portion ofthe each of the plurality of polysilicon films, the portion forming thecorresponding one of the plurality of transistors.

(6) In the display panel according to the item (1), the gate metal layerincludes two gate metals, and the plurality of transistors are arrangedin the zigzag pattern for each one of the plurality of transistors.

(7) In the display panel according to the item (6), the plurality offirst contacts and the plurality of second contacts are respectivelyarranged in the zigzag patterns in a direction in which the plurality ofpads are arranged.

(8) In the display panel according to the item (7), the plurality offirst contacts and the plurality of second contacts form one contact rowbetween the two gate metals.

(9) In the display panel according to the item (7), the display panelfurther includes a plurality of metal wirings in a metal wiring layer.The metal wiring layer is formed as a layer different from thepolysilicon layer and the gate metal layer. Each of the plurality ofmetal wirings is connected to a corresponding one of the plurality offirst contacts and a corresponding one of the plurality of secondcontacts. A width of the each of the plurality of metal wirings issmaller than widths of each of the plurality of first contacts and eachof the plurality of second contacts.

(10) In the display panel according to the item (8), the two gate metalstraverse the plurality of metal wirings connected to the plurality offirst contacts and the plurality of second contacts forming the onecontact row.

(11) In the display panel according to the item (1), the width of theportion of the each of the plurality of polysilicon films, the portionforming the corresponding one of the plurality of transistors, is largerthan widths of each of the plurality of first contacts and each of theplurality of second contacts.

(12) In the display panel according to the item (1), the display panelfurther includes an insulating layer between the polysilicon layer andthe gate metal layer.

The display panel, on which the highly sophisticated driver having anextremely small distance between the output terminals without the RGBswitching function is to be mounted, can include the inspection circuitin which the desired width of each of the inspection transistors isensured.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a schematic diagram illustrating a liquid crystal displaydevice according to an embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating a liquid crystal displaypanel according to the embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating a QD lighting inspectioncircuit for the liquid crystal display panel according to the embodimentof the present invention;

FIG. 4 is an enlarged sectional view of the QD lighting inspectioncircuit, taken along the line IV-IV of FIG. 3;

FIG. 5 is an enlarged sectional view of the QD lighting inspectioncircuit, taken along the line V-V of FIG. 3;

FIG. 6 is a schematic diagram illustrating a modification example of theQD lighting inspection circuit for the liquid crystal display panelaccording to the embodiment of the present invention;

FIG. 7 is an enlarged sectional view of the QD lighting inspectioncircuit, taken along the line VII-VII of FIG. 6;

FIG. 8 is an enlarged sectional view of the QD lighting inspectioncircuit, taken along the line VIII-VIII of FIG. 6;

FIG. 9 is a schematic diagram illustrating a conventional display panel;

FIG. 10 is a schematic diagram illustrating another conventional displaypanel; and

FIG. 11 is a diagram for illustrating problems to be solved by thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

A display panel according to an embodiment of the present invention isobtained by providing an inspection circuit in a driver installationregion of, for example, an LTPS-TFT liquid crystal display panel. Thedriver to be provided does not have an RGB switching function.

FIG. 1 is a block diagram illustrating a schematic configuration of aliquid crystal display device according to the embodiment of the presentinvention. As illustrated in FIG. 1, the liquid crystal display deviceaccording to this embodiment includes a TFT substrate 101 and a countersubstrate 102. Pixel electrodes, thin-film transistors (hereinafter,abbreviated as TFTs), and the like are provided on the TFT substrate101, whereas a color filter and the like are formed on the countersubstrate 102. The TFT substrate 101 and the counter substrate 102 arebonded to each other by a sealing material provided in a frame-likepattern on the respective frame regions of the TFT substrate 101 and thecounter substrate 102. Then, liquid crystal is injected and sealedinside the sealing material between the substrates 101 and 102 through aliquid-crystal injection port provided to a part of the sealingmaterial. Then, polarizing plates are bonded on the respective outersurfaces of the substrates 101 and 102 to constitute the liquid crystaldisplay device. Specifically, the liquid crystal is sandwiched betweenthe pair of substrates.

The TFT substrate 101 has a larger area than that of the countersubstrate 102. In a region 105 of the TFT substrate 101, which does notoverlap the counter substrate 102, a driver 103 for driving the TFTs ismounted. In an area of the region 105 on the side of the driver 103,which is opposite to the counter substrate 102, a flexible wiring board104 is provided.

Although the example where the liquid crystal display device is drivenby the driver 103 is described in this embodiment, a driver circuit mayalternatively be formed on the TFT substrate 101 by using the TFTs orthe like. In addition, the color filter may be provided on the TFTsubstrate 101 instead of being provided on the counter substrate 102.Further, when the liquid crystal display device uses a field sequentialmethod, the color filter is not required. Instead, three-color lightsources, that is, RGB light sources are used. Moreover, counterelectrodes are provided on the counter substrate 102 in the case where aTN or VA method is used for the liquid crystal display device, whereasthe counter electrodes are provided on the TFT substrate 101 in the casewhere an in-plane switching (IPS) method is used for the liquid crystaldisplay device.

FIG. 2 is a schematic diagram of a display panel including inspectiontransistors provided in a driver installation region in the case wherethe driver does not have an RGB switching function. FIG. 2 illustrates astate before the driver is provided on the TFT substrate 101 illustratedin FIG. 1. As illustrated in FIG. 2, a display panel 200 includes apixel region section 203 and a driver region section 205. The pixelregion section 203 includes a pixel region 201 and a peripheral region202 corresponding to a peripheral area surrounding the pixel region 201,whereas the driver region section 205 includes a driver installationregion 204 where the driver is provided and the like. In this case, thedriver installation region 204 is a region where the driver is providedafter the QD lighting inspection is conducted.

In the driver installation region 204, a plurality of inspectiontransistors 206 are sequentially arranged so as to respectivelycorrespond to R-, G-, and B-pixels provided in the pixel region 201.Sources of the inspection transistors 206 are respectively connected tothe R-, G-, B-pixels provided in the pixel region 201 by source wirings210, 211, and 212. Drains of the inspection transistors 206 arerespectively connected to an R drain-line inspection terminal 213, a Gdrain-line inspection terminal 214, and a B drain-line inspectionterminal 215 through an R inspection wiring 207, a G inspection wiring208, and a B inspection wiring 209, respectively. Gates of theinspection transistors 206 are connected to a gate terminal 217 througha gate wiring 216.

Although the R inspection wiring 207, the G inspection wiring 208, andthe B inspection wiring 209 are arranged in this order from the sidecloser to the inspection transistors 206 in FIG. 2, the R inspectionwiring 207, the G inspection wiring 208, and the B inspection wiring 209may be arranged in a different order. Moreover, the arrangement of theinspection transistors 206 illustrated in FIG. 2 is schematicallyillustrated and therefore is not limited thereto. The details of thearrangement of the inspection transistors 206 are described below.

The display panel 200 having the configuration as described above isinspected in the following manner, for example. A predetermined voltageis applied in a predetermined form to each of the R drain-lineinspection terminal 213, the G drain-line inspection terminal 214, the Bdrain-line inspection terminal 215, and the gate terminal 217 to observea display state of the display panel 200. In this manner, breaking ofeach color video line or short-circuiting between the adjacent videolines can be inspected.

FIG. 3 is a schematic diagram of an inspection circuit in whichtransistor groups, each including three adjacent transistors, arearranged in a zigzag pattern, and illustrates the periphery of theinspection transistors 206 illustrated in FIG. 2 in an enlarged manner.FIG. 4 is an enlarged sectional view taken along the line IV-IV of FIG.3, and FIG. 5 is an enlarged sectional view taken along the line V-V ofFIG. 3. As illustrated in FIGS. 3 to 5, the inspection circuit includingthe inspection transistors or the like includes a gate metal layer 301,a polysilicon layer 302, an SD metal layer 303, and insulating layers501, 502, and 503. Polysilicon films 350 described below are formed inthe polysilicon layer 302, whereas a gate metal 390 is formed in thegate metal layer 301. Pad connection contacts 310, inspection wiringconnection contacts 320, contacts 401 and 404, an R inspection wiring360, a G inspection wiring 361, a B inspection wiring 362, and metalwirings 340, 400, 402, and 406 for connection to the pad connectioncontacts 310 and the like are formed in the SD metal layer 303.

As illustrated in FIG. 3, pads 330 for receiving output terminals of thedriver 103 are formed in the driver installation region 204 of thedisplay panel 200. The pads 330 are connected to the pad connectioncontacts 310 through metal wirings 340, respectively. At the positionsopposed to the pad connection contacts 310, the inspection wiringconnection contacts 320 are formed. Further, the inspection wiringconnection contacts 320 are connected to the R inspection wiring 360,the G inspection wiring 361, and the B inspection wiring 362 in thisorder from the left of FIG. 3.

The R inspection wiring 360, the G inspection wiring 361, and the Binspection wiring 362 are arranged in this order from the side closer tothe inspection wiring connection contacts 320 so as to be in parallel tothe inspection wiring connection contacts 320. An inspection wiringconnection contact 321 corresponding to the first inspection wiringconnection contact 320 from the left of FIG. 3 is connected to the Rinspection wiring 360 through an intermediation of the metal wiring 400.

An inspection wiring connection contact 322 corresponding to the secondinspection wiring connection contact 320 from the left is firstconnected to the contact 401 adjacent thereto through an intermediationof the metal wiring 402 and is then connected to the G inspection wiring361 through an intermediation of a wiring traversing line 403 and thecontact 404. The wiring traversing line 403 is formed in the gate metallayer and intersections the R inspection wiring 360 in an insulatedstate. The contact 404 is formed on the G inspection wiring 361.

An inspection wiring connection contact 323 corresponding to the thirdinspection wiring connection contact 320 from the left is firstconnected to a contact 405 adjacent thereto through an intermediation ofthe metal wiring 406 and is then connected to the B inspection wiring362 through an intermediation of a wiring traversing line 407 and acontact 408, as in the case of the second inspection wiring connectioncontact 322. The wiring traversing line 407 is formed in the gate metallayer and intersects the R inspection wiring 360 and the G inspectionwiring 361 in an insulated state. The contact 408 is formed on the Binspection wiring 362. The fourth and subsequent inspection wiringconnection contacts 320 are sequentially connected to the R inspectionwiring 360, the G inspection wiring 361, and the B inspection wiring 362in the same manner.

The positions of the R inspection wiring 360, the G inspection wiring361, and the B inspection wiring 362, and the inspection wiringconnection contacts 320, which are described above, are merely anexample, and are not limited thereto as long as the R inspection wiring360, the G inspection wiring 361, and the B inspection wiring 362 arerespectively connected to the inspection wiring connection contacts 320in an appropriate manner. Moreover, the number of the pad connectioncontacts 310 and the number of the inspection wiring connection contacts320 are not limited to those illustrated in FIG. 3. Further, thepositions of the pads 330 may be changed according to the shapes of theoutput terminals of the driver 103.

Each of the pad connection contacts 310 and a corresponding one of theinspection wiring connection contacts 320 are connected to each other bythe polysilicon film 350 formed in the polysilicon layer 302. Each ofthe polysilicon films 350 includes a transistor formation region 420 anda wiring region 430. In a part of the transistor formation region 420,an inspection transistor 410 is formed. The wiring region 430 has asmaller width than that of the transistor formation region 420 and isused as a wiring for connection to a corresponding one of the padconnection contacts 310 and a corresponding one of the inspection wiringconnection contacts 320. The width of the transistor formation region420 is larger than those of each of the pad connection contacts 310 andeach of the inspection wiring connection contacts 320.

For example, as illustrated in FIG. 3, each of the first to thirdpolysilicon films 350 from the left has the transistor formation region420 on the side closer to the inspection wiring connection contact 320.On the other hand, each of the fourth to sixth polysilicon films 350from the left has the transistor formation region 420 on the side closerto the pad connection contact 310. In the same manner, for the seventhand subsequent polysilicon films 350, the transistor formation regions420 are formed in a zigzag pattern alternately for each set of threeadjacent polysilicon films 350.

In the set of three adjacent polysilicon films 350, the transistorformation region 420 of the leftmost polysilicon film 350 illustrated inFIG. 3 is formed to have a width which is extended to the left. On theother hand, each of the transistor formation regions 420 of theremaining two polysilicon films 350 is formed to have a width which isextended to the right. The pattern as described above is selected forefficiently using a limited space between the pad connection contacts310 and the inspection wiring connection contacts 320.

A part of the wiring region 430 of the polysilicon film 350 from thetransistor formation region 420 to a corresponding one of the padconnection contacts 310 or a corresponding one of the inspection wiringconnection contacts 320, which has a longer distance, can have a smallerwidth than that of another part of the wiring region 430, which has ashorter distance from the transistor formation region 420 to the otherone of the corresponding one of the pad connection contacts 310 and thecorresponding one of the inspection wiring connection contacts 320.Moreover, the width of the part of the wiring region 430, which has thelonger distance, can be smaller than that of the pad connection contact310 or the inspection wiring connection contact 320.

A central part of each of the wiring regions 430 on the second and thirdpad connection contacts 310 side from the left of FIG. 3 is formedcloser to the leftmost polysilicon film 350 as viewed from acorresponding one of the pad connection contacts 310 and a correspondingone of the inspection wiring connection contacts 320. Each of the fourthand sixth polysilicon films 350 from the left is formed closer to thefifth polysilicon film 350 as viewed from a corresponding one of the padconnection contacts 310 and a corresponding one of the inspection wiringconnection contacts 320. The seventh and subsequent polysilicon films350 are arranged sequentially in the same pattern.

The single gate metal 390 is formed in the gate metal layer 301. Thegate metal 390 is formed so as to traverse each of the polysilicon films350 formed in the aforementioned manner. Then, the inspection transistor410 is formed in a portion where the gate metal 390 overlaps each of thepolysilicon films 350. The gate metal 390 is formed avoiding the wiringregion 430 of each of the polysilicon films 350 so as to prevent thetransistor from being formed in a position other than in a predeterminedone.

The inspection transistors 410 are formed in the aforementioned manner,and the sets of the inspection transistors 410, each including threeadjacent inspection transistors 410, are arranged in a zigzag pattern ina direction in which the pad connection contacts 310 and the inspectionwiring connection contacts 320 are arranged. In other words, a pluralityof transistor rows, each including three adjacent inspection transistors410, are arranged in a zigzag pattern. When the side of the inspectionwiring connection contacts 320 is viewed from the side of the padconnection contacts 310, there is an overlapping portion for each set oftwo adjacent transistor rows.

Next, a sectional structure of the periphery of the inspectiontransistors 410 is described. As illustrated in FIGS. 4 and 5, thepolysilicon layer 302 is formed on the insulating layer 501. On thepolysilicon layer 302, the gate metal layer 301 is formed with theinsulating layer 502 interposed therebetween. On the gate metal layer301, the insulating layer 503 is formed. On the insulating layer 503,the SD metal layer 303 is formed. In a portion where the pad connectioncontact 310 is formed, the SD metal layer 303 is formed to pass throughthe insulating layers 503 and 502 so as to be brought into contact withan upper part of the polysilicon layer 302.

The transistor formation regions 420 and the wiring regions 430 of theset of three adjacent polysilicon films 350 described above are formedin the polysilicon layer 302. Then, the gate metal 390 formed in thegate metal layer 301 is formed above the transistor formation regions420 of the set of three adjacent polysilicon films 350 so as to coverthe transistor formation regions 420 through an intermediation of theinsulating layer 502. Here, as viewed from the cross section taken alongthe line V-V of FIG. 3, the gate metal 390 is formed above thetransistor formation region 420, as illustrated in FIG. 5.

In the aforementioned structure, each of the inspection transistors 410is formed by the transistor formation region 420 of the polysilicon film350 and the gate metal 390 provided above the transistor formationregion 420. Specifically, the inspection transistor 410 is formed by twolayers, that is, the polysilicon layer 302 and the gate metal layer 301.

The gate metal layer 301 is formed of a conductive metal such asmolybdenum and is formed to have a shape as illustrated in FIG. 4through known lithography step and etching step. Each of the insulatinglayers 501, 502, and 503 is made of, for example, silicon dioxide (SiO₂)and is formed by a CVD method or the like. The polysilicon film 302 isformed, for example, of amorphous silicon by the CVD method. Afteramorphous silicon is crystallized into polycrystalline silicon by laserannealing, the obtained polycrystalline silicon is processed to have ashape as illustrated in FIGS. 3 to 5 through, for example, the knownlithography step and etching step to form the polysilicon layer 302.Similarly, the SD metal layer 303 is formed to have a shape asillustrated in FIGS. 3 to 5 through the known lithography step andetching step. The SD metal layer 303 is formed of the same metal as thatof a source electrode or a drain electrode of each of the TFTs providedin the pixel region 201.

The known lithography step is, for example, as follows. First, aphotoresist is applied onto an insulating film. Then, the photoresist isirradiated with an ultraviolet ray or the like through an intermediationof a photomask having a predetermined pattern. When a patterncorresponding to the pattern on the photomask is transferred to thephotoresist, the photoresist has a UV ray-irradiated portion and anunirradiated portion. In the UV ray-irradiated portion of thephotoresist, a chemical reaction occurs. Then, the portion of thephotoresist, in which the chemical reaction occurs, or the portion ofthe photoresist, in which no chemical reaction occurs, is removed by adevelopment process to form the resist pattern.

By configuring the display panel 200 according to this embodiment asdescribed above, the limited space between the pad connection contacts310 and the inspection wiring connection contacts 320 can be efficientlyused to ensure a larger width for each of the transistor formationregions 420. As a result, a large width can be ensured for each of theinspection transistors 410.

More specifically, for example, as illustrated in FIG. 3, a distancefrom a left end of the leftmost transistor formation region 420 to aright end of the third transistor formation region 420 from the left, isensured to be larger than a distance from a left end of each of thefirst pad connection contact 310 and the first inspection wiringconnection contact 320 to a right end of each of the third padconnection contact 310 and the third inspection wiring connectioncontact 320. Therefore, as compared with the case illustrated in FIG.11, a larger width can be ensured for each of the inspection transistors410.

For example, when a distance between the centers of the contacts in adirection in which the pads 330 are arranged according to the intervalsbetween the output terminals of the driver is 15 μm, a width of 13 μm orlarger, which is required as the width of the inspection transistor 410,can be ensured. As a result, the QD lighting inspection for the displaypanel 200 can be appropriately conducted.

Although the sets, each including three adjacent inspection transistors410, are arranged in the zigzag pattern in this embodiment, the numberof adjacent inspection transistors 410 constituting each of the setsarranged in the zigzag pattern may be other than three. In particular,it is preferred that the number of adjacent inspection transistors 410constituting each of the sets be two or larger and four or smaller.

In this embodiment, the pad connection contacts 310 correspond to aplurality of first contacts recited in the claims, whereas theinspection wiring connection contacts 320 correspond to a plurality ofsecond contacts recited in the claims.

MODIFICATION EXAMPLE

FIG. 6 is a schematic diagram illustrating a modification example of theembodiment of the present invention. In contrast to the embodimentdescribed above, pad connection contacts 610 are arranged in a zigzagpattern in the direction in which the pads 330 are arranged, that is, ina horizontal direction of FIG. 6 in this modification example.Similarly, inspection wiring connection contacts 620 are arranged in azigzag pattern in the direction in which the pads 330 are arranged.Moreover, inspection transistors 710 are arranged in a zigzag pattern inthe direction in which the pads 330 are arranged, for each inspectiontransistor 710. Further, in contrast to the gate metal 390 described inthe above-mentioned embodiment, two gate metals 690 and 691 areprovided. The gate metals 690 and 691 may be connected to each other atone ends thereof.

More specifically, for example, as illustrated in FIG. 6, the padconnection contacts 610 and the inspection wiring connection contacts620 are arranged in the zigzag pattern so that a contact row 810obtained by sequentially arranging the even-numbered pad connectioncontacts 610 from the left and the odd-numbered inspection wiringconnection contacts 620 from the left is formed. Specifically, thecontact row 810 is formed so that the even-numbered pad connectioncontacts 610 and the odd-numbered inspection wiring connection contacts620 are sequentially arranged. The contact row 810 obtained by thearrangement as described above is located between the gate metal 690 andthe gate metal 691, which are arranged at a distance from each other.

Moreover, the odd-numbered pad connection contacts 610 from the left arearranged in the direction in which the pads 330 are arranged, on theside of the contact row 810, which is closer to the pads 330. On theother hand, the even-numbered inspection wiring connection contacts 620from the left are arranged in the direction in which the pads 330 arearranged, on the side of the contact row 810, which is opposite to theside where the pads 330 are provided.

The odd-numbered pad connection contacts 610 are connected to the pads330 as in the embodiment described above. However, the even-numbered padconnection contacts 610 are connected to the pads 330 through metalwirings 820.

An R inspection wiring 660, a G inspection wiring 661, and a Binspection wiring 662 are formed in this order on the side closer to theinspection wiring connection contacts 620 so as to be parallel in thedirection in which the pads 330 are arranged. The inspection wiringconnection contacts 620 are connected to the R inspection wiring 660,the G inspection wiring 661, and the B inspection wiring 662.

More specifically, in this modification example, for example, aninspection wiring connection contact 621 corresponding to the leftmostone of the plurality of inspection wiring connection contacts 620 isconnected to the R inspection wiring 660 through an intermediation of ametal wiring 831, as illustrated in FIG. 6.

An inspection wiring connection contact 622 corresponding to the secondinspection wiring connection contact 620 from the left is extended to acontact 701 formed below the inspection wiring connection contact 622adjacent thereto in FIG. 6 through a metal wiring 832. Then, from thecontact 701, the inspection wiring connection contact 622 bypasses the Rinspection wiring 660 with a wiring traversing line 842, which is formedin the gate metal layer and intersects the R inspection wiring 660 in aninsulate state, so as to be connected to the G inspection wiring 661through a contact 702 formed on the G inspection wiring 661.

An inspection wiring connection contact 623 corresponding to the thirdinspection wiring connection contact 620 from the left is extended to acontact 703 formed between the second inspection wiring connectioncontact 622 and a fourth inspection wiring connection contact 624through a metal wiring 833. Then, the inspection wiring connectioncontact 623 bypasses the R inspection wiring 660 and the G inspectionwiring 661 with a wiring traversing line 843 connected to the contact703 so as to be connected to the B inspection wiring 662 through acontact 704 formed on the B inspection wiring 662. The wiring traversingline 843 is formed in the gate metal layer and intersects the Rinspection wiring 660 and the G inspection wiring 661 in an insulatedstate.

The fourth inspection wiring connection contact 624 is connected to theR inspection wiring 660 through an intermediation of a metal wiring 834extended downward in FIG. 6.

A fifth inspection wiring connection contact 625 is extended through ametal wiring 835 to a contact 705 formed between the fourth inspectionwiring connection contact 624 and a sixth inspection wiring connectioncontact 626. Then, the fifth inspection wiring connection contact 625bypasses the R inspection wiring 660 with a wiring traversing line 845connected to the contact 705 so as to be connected to the G inspectionwiring 661 through a contact 706 formed on the G inspection wiring 661.The wiring traversing line 845 is formed in the gate metal layer andintersects the R inspection wiring 660 in an insulated state.

The sixth inspection wiring connection contact 626 is extended through ametal wiring 836 to a contact 707 formed below the sixth inspectionwiring connection contact 626 adjacent thereto in FIG. 6. Then, from thecontact 707, the sixth inspection wiring connection contact 626 bypassesthe R inspection wiring 660 and the G inspection wiring 661 with awiring traversing line 846 so as to be connected to the B inspectionwiring 662 through a contact 708 formed on the B inspection wiring 662.The wiring traversing line 846 is formed in the gate metal layer andintersects the R inspection wiring 660 and the G inspection wiring 661in an insulated manner.

The seventh and subsequent contacts 620 are connected sequentially tothe R inspection wiring 660, the G inspection wiring 661, and the Binspection wiring 662, as in the case of the first to sixth inspectionwiring connection contacts 621 to 626. In other words, the odd-numberedinspection wiring connection contacts, which form the contact row 810,are extended through metal wirings 830 and are connected to the Rinspection wiring 660, the G inspection wiring 661, and the B inspectionwiring 662. The metal wirings 830 (831, 832, 833, 834, 835, and 836)extended from polysilicon films 650 toward the corresponding inspectionwirings 660, 661, and 662 are formed in the SD metal layer 750.

A width of each of the metal wirings 820 and 830 respectively connectedto the pad connection contacts 610 and the inspection wiring connectioncontacts 620 is smaller than those of each of the pad connectioncontacts 610 and each of the inspection wiring connection contacts 620.

The positions of the R inspection wiring 660, the G inspection wiring661, and the B inspection wiring 662, and the connection method thereforare not limited to the mode of connection illustrated in FIG. 6 as longas the R inspection wiring 660, the G inspection wiring 661, and the Binspection wiring 662 are connected through an intermediation of themetal wirings formed in the SD metal layer, the wirings and the contactsformed in the gate metal layers, and the like without being crossed.

Each of the pad connection contacts 610 and a corresponding one of theinspection wiring connection contacts 620 are connected to each other bythe polysilicon film 650. The pad connection contacts 610 and theinspection wiring connection contacts 620 are respectively arranged inthe zigzag patterns as described above. Therefore, the polysilicon films650 are similarly arranged in the zigzag pattern in the direction inwhich the pads 330 are arranged.

Each of the polysilicon films 650 includes wiring regions 670 and atransistor formation region 630. The wiring regions 670 are respectivelyconnected to a corresponding one of the pad connection contacts 610 anda corresponding one of the inspection wiring connection contacts 620.The transistor formation region 630 has a larger width than that of thewiring regions 670. The width of the transistor formation region 630 islarger than those of each of the pad connection contacts 610 and each ofthe inspection wiring connection contacts 620. In this modificationexample, in contrast to the embodiment described above, the widths ofthe wiring regions 670 connected to the pad connection contacts 610 andthe inspection wiring contacts 620 are substantially the same.

The two gate metals 690 and 691 are formed so as to traverse thetransistor regions 630 of the respective polysilicon films 650. As aresult, the inspection transistors 710 are formed. More specifically,the gate metal 690 is provided so as to traverse the transistor regions630 of the polysilicon films 650, which are formed between theodd-numbered pad connection contacts 610 and the odd-numbered inspectionwiring connection contacts 620 from the left, and the even-numberedmetal wirings 820 from the left.

On the other hand, the gate metal 691 is provided so as to traverse thetransistor regions 630 of the polysilicon films 650, which are formedbetween the even-numbered pad connection contacts 610 and theeven-numbered inspection wiring connection contacts 620 from the left,and the odd-numbered metal wirings 830 (831, 843, and 845) from theleft. As a result, a plurality of the inspection transistors 710, whichare arranged in the zigzag pattern in the direction in which the pads330 are arranged, are formed along the gate metals 690 and 691. Next, asectional structure of the periphery of the inspection transistor 710 isdescribed. Similarly to the embodiment described above, as illustratedin FIG. 7 which is an enlarged sectional view taken along the lineVII-VII of FIG. 6 and FIG. 8 which is an enlarged sectional view takenalong the line VIII-VIII of FIG. 6, a polysilicon layer 730 is formed onan insulating layer 721. On the polysilicon layer 730, a gate metallayer 740 is formed with an insulating layer 722 interposedtherebetween. On the gate metal layer 740, an insulating layer 723 isfurther formed. On the insulating layer 723, an SD metal layer 750 isformed.

As in the embodiment described above, the polysilicon films 650 areformed in the polysilicon layer 730, whereas the gate metals 690 and 691are formed in the gate metal layer 740. The pad connection contacts 610,the inspection wiring connection contacts 620, the metal wirings 820,and the like are formed in the SD metal layer 750. The layers arerespectively made of the same materials as those described in theaforementioned embodiment. In addition, the shapes illustrated in FIGS.7 and 8 are formed by the same methods as those described in theaforementioned embodiment.

As viewed from the cross section of FIG. 7, which is taken along theline VII-VII of FIG. 6, the gate metal 690 is formed in the gate metallayer 740 above the transistor formation region 630 of the polysiliconfilm 650 located to be included in the polysilicon layer 730 so as tocover the transistor formation region 630. At this time, as viewed fromthe cross section of FIG. 8, which is taken along the line VIII-VIII ofFIG. 6, the gate metal 690 is formed above a part of the transistorformation region 630 of the polysilicon film 650. Similarly, the gatemetal 691 is formed above the transistor formation region 630 of thepolysilicon film 650 so as to cover the transistor formation region 630.

In the structure described above, the inspection transistors 710 areformed by the gate metals 690 and 691, each being formed so as totraverse the transistor formation regions 630 of the polysilicon films650. Specifically, each of the inspection transistors 710 is formed bytwo layers, that is, the polysilicon layer 730 and the gate metal layer740.

According to the structure described above, for each of the inspectiontransistors 710 arranged in the zigzag pattern, a width of each of thetransistor formation regions 630, which is equal to a distance betweenthe two metal wirings respectively connected to the contacts, forexample, equal to a distance between the metal wirings 820 connected tothe even-numbered pad connection contacts 610 illustrated in FIG. 6, canbe ensured. Moreover, if the short-circuiting between the polysiliconfilms 650 and the like are not taken into consideration, the width ofeach of the transistor formation regions 630, which is equal to adistance between two contacts, for example, a distance between thecenters of the even-numbered pad connection contacts 610 of FIG. 6, canbe ensured.

Moreover, by arranging the pad connection contacts 610 and theinspection wiring connection contacts 620 in the zigzag patterns so asto form the contact row 810 as described above, a space for theinspection transistors 710 can be efficiently ensured in a limited spacebetween the pad connection contacts 610 and the inspection wiringconnection contacts 620.

Further, in this modification example, the width of each of the wiringregions 670 is not required to be smaller than a distance between theadjacent pad connection contacts 610 or a distance between the adjacentinspection wiring connection contacts 620, unlike the embodimentdescribed above. Therefore, a sufficiently large width of each of theinspection transistors 710 can be more efficiently ensured.

More specifically, for example, when a distance between the centers ofthe contacts in the direction in which the pads are arranged accordingto the intervals between the output terminals of the driver is 15 μm, awidth of 22 μm is ensured for the width of each of the inspectiontransistors. Therefore, a width of 13 μm or larger, which is necessaryas the width of the inspection transistor, can be ensured.

In this modification example, the pad connection contacts 610 correspondto the plurality of first contacts recited in the claims, whereas theinspection wiring connection contacts 620 correspond to the plurality ofsecond contacts recited in the claims.

The present invention is not limited to the liquid crystal displaypanel. The present invention is also applicable to, for example, othertypes of display panels such as an organic EL display panel. Moreover,the present invention is not limited to the embodiment and modificationexample described above, and therefore modification examples other thanthat described above are possible. The aforementioned structure can bereplaced by substantially the same structure, a structure having thesame functions and effects, or a structure enabling the achievement ofthe same object.

While there have been described what are at present considered to becertain embodiments of the invention, it will be understood that variousmodifications may be made thereto, and it is intended that the appendedclaims cover all such modifications as fall within the true spirit andscope of the invention.

1. A display panel comprising: a plurality of pads configured to providea driver thereon; a plurality of first contacts respectively connectedto the plurality of pads; a plurality of second contacts respectivelyprovided so as to be opposed to the plurality of first contacts; apolysilicon layer configured to form a plurality of polysilicon films toconnect the plurality of first contacts and the plurality of secondcontacts to each other; and a gate metal layer different from thepolysilicon layer, wherein the gate metal layer forms at least one gatemetal, wherein the gate metal layer traverses the plurality ofpolysilicon films so as to form a plurality of transistors, wherein theplurality of transistors are arranged in a zigzag pattern for eachtransistor set including at least one adjacent transistor, and wherein awidth of a portion of each of the plurality of polysilicon films, theportion forming a corresponding one of the plurality of transistors, islarger than a width of another portion of the each of the plurality ofpolysilicon films, the another portion being connected to acorresponding one of the plurality of first contacts and the pluralityof second contacts.
 2. The display panel according to claim 1, whereinthe plurality of transistors comprise a plurality of transistor rows,each including at least two adjacent transistors, and the plurality oftransistor rows are arranged in the zigzag pattern.
 3. The display panelaccording to claim 2, wherein a number of the transistors included ineach of the plurality of transistor rows is four or less.
 4. The displaypanel according to claim 2, wherein the plurality of transistor rowshave an overlapping portion when the plurality of second contacts areviewed from the plurality of first contacts.
 5. The display panelaccording to claim 2, wherein a width of a portion of the each of theplurality of polysilicon films located between the plurality oftransistor rows is smaller than the width of the portion of the each ofthe plurality of polysilicon films, the portion forming thecorresponding one of the plurality of transistors.
 6. The display panelaccording to claim 1, wherein the gate metal layer comprises two gatemetals, and the plurality of transistors are arranged in the zigzagpattern for each one of the plurality of transistors.
 7. The displaypanel according to claim 6, wherein the plurality of first contacts andthe plurality of second contacts are respectively arranged in the zigzagpatterns in a direction in which the plurality of pads are arranged. 8.The display panel according to claim 7, wherein the plurality of firstcontacts and the plurality of second contacts form one contact rowbetween the two gate metals.
 9. The display panel according to claim 7,further comprising a plurality of metal wirings in a metal wiring layer,wherein the metal wiring layer is formed as a layer different from thepolysilicon layer and the gate metal layer, wherein each of theplurality of metal wirings is connected to a corresponding one of theplurality of first contacts and a corresponding one of the plurality ofsecond contacts, and wherein a width of the each of the plurality ofmetal wirings is smaller than widths of each of the plurality of firstcontacts and each of the plurality of second contacts.
 10. The displaypanel according to claim 8, wherein the two gate metals traverse theplurality of metal wirings connected to the plurality of first contactsand the plurality of second contacts forming the one contact row. 11.The display panel according to claim 1, wherein the width of the portionof the each of the plurality of polysilicon films, the portion formingthe corresponding one of the plurality of transistors, is larger thanwidths of each of the plurality of first contacts and each of theplurality of second contacts.
 12. The display panel according to claim1, further comprising an insulating layer between the polysilicon layerand the gate metal layer.